Hawk Talk

[hertz9753]

Isn't that something that an English hitman uses to keep his gun quiet?

[Ariel Red Hunter]

Originally Posted by hertz9753

Isn't that something that an English hitman uses to keep his gun quiet?

Funny, but not quite. Brooklands was a pre-war racing venue that required mufflers (silencers to the British).

[hertz9753]

http://www.austin7club.org/How%20To%2011.htm

It's also a race track in the UK built nine years before my dad was born and you can still buy the silencers from many websites in the UK.

http://www.classicmotorcyclespares.c...html#Silencers

Most people don't know how much good info is in your posts but just like you I am a knowledge sponge.

[pete]

Originally Posted by hertz9753

Most people don't know how much good info is in your posts but just like you I am a knowledge sponge.

yer a bit of stuff yer tend to forget about over the years...




...

[Ariel Red Hunter]

Originally Posted by hertz9753

http://www.austin7club.org/How%20To%2011.htm

It's also a race track in the UK built nine years before my dad was born and you can still buy the silencers from many websites in the UK.

http://www.classicmotorcyclespares.c...html#Silencers

Most people don't know how much good info is in your posts but just like you I am a knowledge sponge.

A racing venue is just fancy-pants verbiage for a race track. What they found out, eventually, on the Prony Brake (a mechanical dynomometer) was that a well selected Brooklands Silencer actually increased horse power by 3 or 4 percent over a straight pipe.

[Ariel Red Hunter]

A Prony Brake is a method of reading the torque of a rotating shaft. It has been around for at least 150 years. You will immedietly grasp the fact that a crankshaft on a internal combustion engine is a rotating shaft. If you could mount a drum brake on the crankshaft, have a freely rotating brake backing plate, connect a bar exactly one foot long to said backing plate, arrange an accurate scale for the one foot long lever (one foot from the crank center line), you would have a Prony Brake. And have an answer in foot ponds. Warm the engine up, and start reading the numbers off of the scale at, say, 250 rpm intervals. Obviously, as the rpm's climbed, you had to tighten the brake bands or shoes in order to hold the rpms steady at that rpm. Yes, you had to cool the brakes. Brake bands were used for a long time, because you could cool them by dripping water on the band and drum. If you want to build one of these brakes in your garage, you can do what I did, and use a Farmall "M" brake from either the left or right side to build the brake part. And yes, I had a beer keg of water that dripped down to keep it from over heating. The "M" has external brake bands, that's why I used that brake. And now you know where the phrase "Brake Horsepower" comes from. B.H.P. If you decide to build your own Prony Brake, let me know - I know where to find the parts.

[Ariel Red Hunter]

OK, you've already decided (I think) how far you want to go with the engine. So let's see where we can reduce the losses. Perhaps the first thing is the drive chain run. First problem is the counter-shaft sprocket. The wiggle is not good, so we are going to eventually shim it one way or another to get rid of the wiggle, and have it absolutely dead nuts centered on the rear wheel sprocket. To do this we have to drop the chain and run a straight edge from the rear sprocket to the front sprocket. If they are more than a quarter inch out of true, the first place to look is at the rear wheel alignment with the front wheel, and making sure that the front tire is centered in the rear tire. I use two bed frame irons and run them from the back wheel to past the front. That will tell you if the rear tire is out of line with the front ("dog tracking"). Correct that problem first. If all is right, and I mean RIGHT!, then check the sprocket run. It is possible you will have to shim either to get that dead on. I think this is the perfect time to replace the counter shaft mounting bolts, and the countershaft sprocket cover with high quality allen screws. In Metric sizes, of course. So now you have reduced chain losses to the minimum, right? Next is the chain. I prefer a high quality non o-ring chain. What? Why? Because of less drag, or frictional loss. When you are playing with around fifteen horsepower, and want speed, you have to cut every loss you can. Cutting losses is usually much cheaper than adding horsepower. If we can save only one and one-half horsepower, that is 10%! Next is wheels and tires. Scrub losses from wide tires eat horsepower. If your buddie does everything you do, and stays with 3.00X21 front and 4.20X18 rear, but if you run a 2.75X21 speedmaster front, and change to a 21 inch rear rim and mount a 3.00X21 on the rear, you will out run him on top end every time. And maybe corner faster as well. Don't believe me? Look at bicycles. Notice that the faster one run large diameter but skinny tires. They don't build them that way for looks.

[Ariel Red Hunter]

Hopefully, Those legions of my readers who suffered different levels of heart failure yesterday over my comments about why you want to run a 21 inch rear wheel, if you are looking for all the speed you can get, have recovered. Indigestion is, I hope, also under control. Somewhere in the dim, distant past, I read that a human being can produce between 1/4 and 3/8 of a horsepower for any longer than a few moments. So therefore, a bicycle has to be designed to get the utmost out of the available horsepower. A motorcycle could be described as a sophisticated motorized bicycle. Now the Hawk is designed as a dual purpose motorcycle, obviously. But, if we choose to spend 90% on pavement, and only ride dirt/gravel roads and hard packed trails 10% of the time, and want all the speed we can get, a 21 inch rear is one of the steps to getting the highest possible maximum speed out of this particular scoot. My Ariel Red Hunter came from the factory with a 2.75X21 inch front tire and wheel, and a 3.00X20 rear tire and wheel. But good luck finding 3.00X20 tires and rims today. My Ariel came with an Avon Speedmaster front tire (ribbed), and an Avon speedmaster rear, which was not ribbed, but wiggly-grooved. And moderatly high tire pressures. About 25 front, and 32 rear, if memory serves. And it takes a different, older riding style to get the best out of it. You don't throw the bike in the corners, you squeeze it, keeping your knees in. Smooth riding. If you are up to a little youtube-ing, I suggest you watch Mike Hailwood's technique in the race at Mallory Park in 1978, riding a Ducati V-twin against all the super horsepower 4 bangers. Watch how smoothly he rides. This is a fifteen minute education on how to ride a skinny tired, comparatively low horsepower machine.

[BlackBike]

I was worried, thinking you were going for a pair of crank arms and petals for that extra 3/8 hp boost

[Ariel Red Hunter]

Originally Posted by BlackBike

I was worried, thinking you were going for a pair of crank arms and petals for that extra 3/8 hp boost

Just LUV a guy with a sense of humor! Really I do. But, this proves that at least one guy read it.

[Ariel Red Hunter]

If you choose to re-make the Hawk into a corner scratcher, like I have been talking about, something is going to have to be done about the swing arm bushings. When you put your Geoff Duke face on, you won't like that hinged-in-the-middle feeling. Urethane bushings are better than what's in there - and bronze bushings will really tighten things up. Front fork oil up-graded to at least Dexron ATF. If you want it a little firmer, try Mercon ATF. I would try to find Ferodo lined pads for the brakes. Remember, if you put Ferodo pads on, you have to warm them up before you get real serious. This is why 175's, 200's and 250's are so much fun. You really get to run the little bastards as hard as you can without getting into serious trouble. Maybe that's why I loved my little Model 14 AJS so much. Just ride the heck out of it, and enjoy. The Model 14 wasn't perfect - it came with 17 inch wheels. Even so, it would get right on down the road. Somewhat the same engine as a Hawk but tuned pretty good right from the factory. My uncle raced a 350 "Cammy" AJS on the board tracks in the 1920's. It was fast, but fragile. His nickname for it was "the valve swallower". The world has made tremendous strides in metalurgy and lubricants since those days. Back to the Hawk-a-thon. Be sure to change the brake fluid to DOT 3 or better. If you want to spend the time and money, you could do some work on the camshaft, to get more overlap. Pull the head to make sure the valve seats are good. If you are going to be running a lot at continious high rpm, look after the valve springs. If you can find high octane fuel without ethenol in it, run that. Pay attention to spoke tension. And have fun.

[Ariel Red Hunter]

I thought I covered reducing friction pretty well, but I just remembered that when I visited Andy Kolbe's BSA/Honda shop in Woodland Hills, Calif., they were working on their Gold Star flat tracker. I think they were getting it ready for the Sacramento Mile. Sacto, we called it. Anyway they were testing various ways to grease the wheel bearings. They spent all afternoon and evening trying different bearing greases. They would grease it up, mount it on the bike, and have the same guy spin the wheel, and time it with a stopwatch until the wheel stopped. Vaseline was the winner. They replaced the modern spring type rubber seals with leather seals that they punched out on the spot. "I can't believe that made any difference" I said. "Oh yeah, the leather seals barely touch the axle, and the tire revolved about 2 minutes longer." That is what is known as taking pains.

[fredweb]

Originally Posted by Ariel Red Hunter

I thought I covered reducing friction pretty well, but I just remembered that when I visited Andy Kolbe's BSA/Honda shop in Woodland Hills, Calif., they were working on their Gold Star flat tracker. I think they were getting it ready for the Sacramento Mile. Sacto, we called it. Anyway they were testing various ways to grease the wheel bearings. They spent all afternoon and evening trying different bearing greases. They would grease it up, mount it on the bike, and have the same guy spin the wheel, and time it with a stopwatch until the wheel stopped. Vaseline was the winner. They replaced the modern spring type rubber seals with leather seals that they punched out on the spot. "I can't believe that made any difference" I said. "Oh yeah, the leather seals barely touch the axle, and the tire revolved about 2 minutes longer." That is what is known as taking pains.

Vaseline has a melting point of 99deg F. I wouldn't expect that to last long in a bearing. It will run out the bearing and probably catch fire after the bearing heats up. The grease being used isn't as important as how its used. If you want to reduce friction use lithium based grease and just barely coat the balls and race. I used to grease the bearings and then use compressed air to blow out the excess. This reduces friction and in turn reduces the heat generated. Vaseline is not a very good idea at all.

[Ariel Red Hunter]

Originally Posted by fredweb

Vaseline has a melting point of 99deg F. I wouldn't expect that to last long in a bearing. It will run out the bearing and probably catch fire after the bearing heats up. The grease being used isn't as important as how its used. If you want to reduce friction use lithium based grease and just barely coat the balls and race. I used to grease the bearings and then use compressed air to blow out the excess. This reduces friction and in turn reduces the heat generated. Vaseline is not a very good idea at all.

I didn't know lithium grease was available in 1960. They may have used the Vaseline for a benchmark. I've used Vaseline grease for this and that for years and never had melting at low temperature problems. I've used it on cows before for barb wire cuts, and their body heat is 104, I think. Anyway that's the number that sticks in my mind. I doubt the flash point for vaseline is anywhere near 99f.

[fredweb]

Originally Posted by Ariel Red Hunter

I didn't know lithium grease was available in 1960. They may have used the Vaseline for a benchmark. I've used Vaseline grease for this and that for years and never had melting at low temperature problems. I've used it on cows before for barb wire cuts, and their body heat is 104, I think. Anyway that's the number that sticks in my mind. I doubt the flash point for vaseline is anywhere near 99f.

The flash point for vaseline is around 200deg F. certainly low enough to be ignited by friction from a poorly lubed bearing. putting vaseline on a cow is a lot different than using it for a bearing grease. My point was that the grease used is less important than application and use provided that the grease actually stays on the bearing surfaces and prevents friction heat. anyone that uses vaseline for bearing grease is asking for trouble. I've only been a mechanical engineer for 25 years but what the hell do i know. go ahead and use vaseline. They will sell you all the bearings you want i suppose.